The present invention relates to a method of resin molding and a resin molding machine, more precisely relates to a method of resin molding and a resin molding machine, in each of which a parting face of a molding die, which includes a pot and a cavity, is covered with release film when a work piece is molded with resin.
Conventionally, in the case of forming a plurality of semiconductor devices, which includes cable layers and electric terminals, e.g., metallic pillars, on a semiconductor wafer, compression molding has been employed so as to fill spaces between the metallic pillars with resin.
The conventional compression molding was disclosed in the Japanese Patent Gazette No. 10-79362. In the conventional method, a semiconductor wafer, which is a work piece to be-molded, is set in a cavity, a resin tablet is mounted on a surface of the wafer, in which the metallic pillars are formed, and the resin tablet is compressed so as to fill the spaces between the metallic pillars with the resin. By filling the spaces, the surface of the wafer can be molded.
However, in the case of molding the semiconductor devices formed on the surface of the semiconductor wafer, the resin is compressed so as to make a thickness of the molding resin layer 0.1 mm or less, so it is difficult to uniformly mold the whole surface of the wafer with the resin. Many of the metallic pillars are extended from the surface with separations of 0.1 mm or less, a diameter of the wafer is 200-300 mm, the melted resin cannot flow smoothly, resin pressure varies and the melted resin is apt to solidify on the way to the cavity, so it is quite difficult to uniformly mold the wafer.
Namely, it is difficult for the conventional compression molding method to uniformly control amount of the resin for molding the work piece and pressure of the melted resin. Even if the resin is overflowed from the cavity, it is still difficult for the compression molding to maintain the resin pressure.
An object of the present invention is to provide a method of resin molding and a resin molding machine, which are capable of uniformly control amount of the resin for molding a work piece and pressure of the melted resin.
To achieve the object, the present invention has following structures.
The method of resin molding of the present invention comprises the steps of:
covering a parting face of one of molding dies, which includes a pot and a cavity, with release film;
setting a work piece to be molded in the cavity;
setting resin in the pot;
clamping parts of the release film, which enclose the work piece except a resin path, by the molding dies;
reducing capacity of the cavity when the parts of the release film are clamped; and
sending the resin from the pot to the cavity so as to mold the work piece in the cavity.
On the other hand, the resin molding machine of the present invention includes molding dies having parting faces, which are covered with release film when a work piece is molded, and one of the molding dies comprises:
a cavity being formed in the parting face;
a movable clamping section for clamping parts of the release film, which enclose the work piece except a resin path;
a resin sending mechanism including a pot, which is formed in the parting face and communicated to the cavity, and a plunger, which is movably provided in the pot and sends resin from the pot to the cavity when the movable clamping section clamps the release film; and
a movable cavity block constituting a part of the cavity, the movable cavity block being moved in the cavity so as to reduce capacity of the cavity.
In the resin molding machine, the overflowed resin, which is overflowed from the cavity when the movable cavity block is moved to reduce the capacity of the cavity, may be returned to the pot so as to push the plunger backward.
In the resin molding machine, an overflow cavity may be formed in the movable clamping section, wherein a part of the overflowed resin is returned to the pot and the rest of the overflowed resin is introduced into the overflow cavity.
The resin molding machine may further comprise heaters, which are provided in the movable cavity block and the other molding die, wherein the heaters heat at lower temperature when the resin is filled in the cavity to mold the work piece, the heaters heat at higher temperature when the movable cavity block is moved to reduce the capacity of the cavity.
In the method and the machine of the present invention, the capacity of the cavity is reduced when the parts of the release film are clamped. By reducing the capacity of the cavity, the melted resin is overflowed from the cavity, so that the resin pressure in the cavity can be close to the resin pressure in the pot and the work pieces can be uniformly molded with a prescribed thickness.
Especially, in the case of molding a surface of a wafer in which metallic pillars are formed, the surface can be uniformly molded. And, front end faces of the metallic pillars are securely covered with the release film, so that the front end faces can be exposed, as electric terminals, after molding. In the case of molding a semiconductor wafer on which a plurality of IC chips are matrically formed, quality of semiconductor devices can be improved.
If the heaters heat at lower temperature when the resin is filled in the cavity to mold the work piece and the heaters heat at higher temperature when the movable cavity block is moved to reduce the capacity of the cavity, the melted resin can be prevented to solidify in a narrow path to the cavity, so that the work piece can be uniformly molded.